The history of music has produced a multitude of different devices, aids, dials, and charts to expedite the learning of musical chords, progressions, inversions, note reading, keyboard and octave structure, and everything else pertaining to the structure of music.
There are also a number of different teaching aids which resemble somewhat the instant device in that they have a display of a piano or organ keyboard with various notes, chords, progressions, inversions and the like aligned with the keys of the keyboard. The general intent of these devices is to instruct the student as to the continuous nature of the scale, and the manner in which all of these various aspects of music correlate with the continuous sequencing of keys and scale tones.
However, the very continuity of the keyboard of a musical instrument is in itself confusing to the student and makes it very difficult to consider the various octaves as having their own separate identity and characteristics, and being correlated with certain notes and note reading.
In such devices as may isolate the octaves for purposes of identification separately from the other octaves, chords are generally taught only in the root, or non-inverted position so that the chords of, for example, the cycle of fourths or fifths will fit within the narrow confines of the isolated octave.